Grand Ayatollah Sayyed Ruhollah Mousavi Khomeini (21 September 1902 - 04 June 1989) was a senior Shi`a (Shi'ite) Muslim cleric, Islamic philosopher and Marja (religious authority), and the political leader of the 1979 Iranian Revolution which saw the overthrow of Mohammad Reza Pahlavi, the last Shah (king) of Iran.

Following the revolution, Ayatollah Khomeini became Supreme Leader of Iran—the paramount symbolic political figure of the new Islamic Republic until his death. Khomeini was known as an anti-colonial leader who created the post-colonial state, Islamic Republic of Iran after a referendum.

Ayatollah Khomeini was a Marja al-Taqlid, ("source of imitation") and important spiritual leader to many Shi'a Muslims.

He was named Time's Man of the Year in 1979 and also one of Time magazine's 100 most influential people of the 20th century.